Server architectures are typically designed to manage power drawn from power supplies based on application loads. Generally, as an application load is increased, the power drawn by a server architecture is increased. Conversely, as the application load is reduced, the power drawn by the server architecture is reduced. When designing a server architecture, servers and their associated power supplies are designed to accommodate peak load estimates. Power supplies used to provide power to servers within a server architecture are often chosen such that a worst case load may be accommodated. For example, blade system power supplies are often designed to support a peak power draw.
Although server designs are sized based on peak load estimates, many server designs often do not operate at or near their peak load estimates. That is, many servers operate at relatively low load, e.g., near idle, conditions for a significant portion of time and, thus, power supplies are not often fully loaded. As the efficiency associated with power supplies decreases as the power drawn from the power supplies decreases, when power supplies are operating at relatively low loads for a significant portion of time, the power supplies are operating with relatively low power efficiency for a significant portion of time.
Multiple power supplies are often used to deliver power within a server architecture, and to share the load substantially equally. While substantially equal load sharing amongst multiple power supplies may enhance the reliability and availability of a server design, efficiency with which power is used may be reduced, as the efficiency associated with a power supply generally decreases as the load or power drawn from the power supply is reduced. Thus, when multiple power supplies are equally sharing a load and are each operating at relatively low loads, the delivered efficiency is compromised.